Gas turbines are widely used in industrial and power generation operations. A typical gas turbine includes an axial compressor at the front, one or more combustors around the middle, and a turbine at the rear. Ambient air enters the compressor, and rotating blades and stationary vanes in the compressor progressively impart kinetic energy to the working fluid (air) to bring it to a highly energized state. The working fluid exits the compressor and flows to the combustors where it mixes with fuel and ignites to generate combustion gases having a high temperature, pressure, and velocity. The combustion gases flow from the combustors through the turbine along a hot gas path. In the turbine, the combustion gases expand to produce work. For example, expansion of the combustion gases in the turbine may rotate a shaft connected to a generator to produce electricity.
It is widely known that the thermodynamic efficiency of a gas turbine increases as the operating temperature, namely the combustion gas temperature, increases. Higher temperature combustion gases contain more energy and produce more work as the combustion gases expand in the turbine. However, higher temperature combustion gases may produce excessive temperatures in the combustor or turbine that can approach or exceed the life limiting temperature of various components along the hot gas path. In addition, changes in operating conditions, such as a change in the ambient temperature, fuel composition, and/or operating level of the gas turbine, may lead to excessive temperatures that may damage various components. As a result, industrial and power generation gas turbines often include control systems that monitor and control the operation of the gas turbines. For example, the control system may monitor various temperatures in the compressor, combustors, or turbine and adjust the operation of one or more components to achieve a desired operating parameter for the gas turbine and/or ensure that various operating limits are not exceeded.
The control system may use multiple sensors installed at multiple locations to fully monitor various parameters of the gas turbine. For example, cameras, gas analyzers, thermocouples, and other sensors known in the art may be installed to monitor conditions in the combustor, in the turbine, or along the hot gas path. The high temperature and pressure conditions in the combustors, turbine, and hot gas path, however, create a hostile environment for the sensors that adversely affects the sensitivity, accuracy, longevity, and overall performance of the sensors. Therefore, a control system that can monitor parameters inside the combustor, turbine, and/or hot gas path without requiring a sensor to be installed inside these components or locations would be desirable.